Revealing mistake: Even though Drillbit's pinkie was supposedly cut off by the sword, you can see it is just bent out of sight.
Continuity mistake: When Wade is at dinner with his family, when his stepdad is talking to him, Wade places his milk down on the table. Then in the next shot it is back in his hand, and then back down again.
Visible crew/equipment: In the scene where Filkins tries to run down the boys with his car, when he spots the boys coming from over a fence, as he stops the car, the camera is reflected briefly in the window. It becomes visible again as Filkins backs his car up.
Factual error: At the resolution of the movie when Filkins is sent back to Hong Kong, in the shot there is a banner written in Hiragana (one of the Japanese alphabets), not Chinese.
Continuity mistake: When Filkins drives his car in order to chase the three boys, before they run into the garage, the rearview mirror disappears and reappears.
Continuity mistake: After the kids sneak Drillbit out of the house when the parents arrive. The skinny kid has his right arm bend up touching the back of his head and it's behind the fat kid, on the next shot both his arms are down and he is a couple steps ahead the fat kid.
Answer: They probably thought that Filkins was a bigger threat.